Method of and apparatus for proportioning gaseous fluids



Nov. 7, 1933. E. x. SCHMIDT 1,933,641

METHOD OF AND APPARATUS FOR PROPORTIONING GASEOUS FLUIDS Filed July 5,1932 2 Sheets-Sheet 1 E. X. SCHMIDT Nov. 7, 1933.

METHOD OF AND APPARATUS FOR PROPORTIONING'GASEOUS FLUIDS Filed July 5.1932 2 Sheets-Sheet 2 iii) Patented Nov. 7, 1933 UNITED STATES PATENTOFFICE METHOD OF AND APPARATUS FOR PRO- PORTIONING GASEOUS FLUIDSApplication July 5, 1932. Serial No. 620,967

17 Claims.

This invention relates to improvements in methods of and apparatus forproportioning gaseous fluids, and although not limited thereto theinvention relates more particularly to methods of and apparatus forproportioning butane gas and air to provide a gaseous mixture ofpredetermined quality or total heating value per unit volume underconditions of relatively wide variations in the demand for the mixture.

An object of the invention is to provide a novel method of varying therate of supply of the gaseous mixture to compensate for variations inthe demand therefor, while insuring a substantially constant quality ortotal heating value per unit volume of the mixture.

Another object is to provide novel means for performing the methodaforementioned.

Another object is to provide a gas making and distributing system of thecharacter aforementioned wherein a plurality of gas making units areemployed, means being provided for automatically effecting operation ofone or more of said units, depending upon the rate of demand for thegaseous mixture.

Another object is to provide such a system wherein continuous operationof one of the gas making units is contemplated,means being provided fortransferring the continuous duty from one to another of the severalunits at will to substantially equalize the Wear upon the units and torender any one of the latter inactive for purposes of repair underconditions of low or minimum demand for the gaseous mixture.

Another object is to improve the details of construction and operationofgas mixing control systems of the character aforementioned.

Other objects and advantages of the invention will hereinafter appear.

The accompanying drawings illustrate certain embodiments of theinvention which will now be described-but it is to be understood thatthe embodiments illustrated are susceptible of modification withoutdeparting from the scope of the appended claims.

In the drawings, Figure 1 is a schematic and diagrammatic view ofa gasmixing control system constructed in accordance with my invention, and

Fig. 2 is a similar view of a modified form of gas mixing controlsystem.

Referring first to Fig. 1, the numeral 5 designates a tank or receptaclewhich may serve as a source of supply of one of the gaseous fluidconstituents of the final gaseous mixture. Thus (Ci. 48ll80) it may beassumed that the tank 5 is partially filled with a volatile hydrocarbonliquid, such as butane,said liquid being inherently vaporable atsubstantially all normal atmospheric temperatures, although if desiredsuitable means (such as an electric heater, not shown) may be associatedwith tank 5 to insure vaporization of the liquid under extremely lowtemperature conditions. The upper portion of tank 5 thus serves as astorage chamber for the vapor under its own pressure, and communicatingwith said upper portion of the tank are a pair of branch pipes orconduits 6 and 7, said conduits having pressure regulating valves 6 and7 therein whereby the pressure in said conduits at the right hand sidesof the valves G and 7 is maintained at a substantially constantpredetermined value.

Also located within conduits 6 and '7 are a pair of adjustable disk--orbutterfly-valves 6 and 7 for controlling the rate of flow of the vaporor gas through said conduits-the latter being further provided withnormally closed electromagnetically operable valves 6 and 7 which arecontrolled in the manner hereinafter described.

As shown the conduit 6 communicates with a conduit 8 the inlet end 8 ofwhich communicates with the atmosphere for induction of air, or saidconduit 8 may be connected with any other source of gas of relativelylow quality or total heating value per unit volume. Conduit 8 in turnleads to the intake end of a positive displacement pump 9, said pumpbeing mechanically connected through the medium of lever 9 fiy-wheel 9and belt 9 with an electric motor 9 for driving thereof at asubstantially constant speed by the latter. The discharge side of pump 9communicates through conduit 10 with a conduit 11 which may communicatedirectly with the discharge line 12 of a distribution system, but asshown a tank 13 is interposed between conduit 11 and discharge line12,-said tank serving as a high-pressure storage receptacle for themixed gases, and a regulating valve 12 being interposed between tank 13and discharge line 12 to maintain a relatively low and substantiallyconstant pressure of the gas mixture flowing through the latter. Anormally closed electromagnetically operative valve 10 is interposedbetween conduits 10 and 11, said valve being controlled in the mannerhereinafter set forth.

Conduit 7 similarly communicates with a conduit 14 the inlet end 14 ofwhich communicates with the atmosphere or some other source ofrelatively lean gas. Conduit l l in turn leads to the intake end of apositive displacement pump 15, said pump being mechanically connectedthrough the medium of lever 15, fly-wheel 15 and belt 15 with anelectric motor 15 for driving thereof at a substantially constant speedby the latter. The discharge side of pump 15 communicates throughconduit 16 with the aforementioned conduit 11,a normally closedelectromagnetically operable valve 16 being interposed between thedischarge side of pump 15 and conduit 11 for operation in the mannerhereinafter set forth. While I have shown pumps 9 and 15 as being oflike size or capacity and adapted for operation at like speeds by therespective motors 9 and 15 ,-it is to be understood that pumps of unlikecapacities may be employed if desired, and motors operable at unlike butconstantly proportional speeds may be substituted for those illustrated.

Associated with the tank 13 and subjected to the pressure conditionswithin the latter are a pair of pressure responsive switches the movablecontactors l7 and 18 of which are adapted for cooperation with pairs ofstationary contacts 17*, 17 and 13 18*, respectively. The pressureresponsive elements of said switches are calibrated differently, and itmay be assumed that the pressure within tank 13 has fallen apredetermined degree below the desired value, with consequent movementof contactor 17 toward the left into engagement with contact 1'7 (asshown). This completes an energizing circuitror the winding of relay19,said circuit extending from line L by conductor 29 through a suitablecurrent-reducing resistance 21, conductor 22 through said winding,conductor 23 through contact 17 and contactor l7, and by conductors 24and 25 to line L Contacts 19 of said relay are adapted upon closurethereof to complete a maintaining circuit for said winding shunting thecontact 17 and contactor l7,--said maintaining circuit being obvious.

Said relay upon closure of its contacts 19 likewise completes anenergizing circuit for the winding 26*: of an electromagneticallyoperable switch 26,-said circuit extending from line L by conductors 25,24 and 27 through said contacts 19 by conductor 28 through the contacts29, 29 and 29 of a double-pole, double-throw transfer switch 29, byconductor 30 through said winding 26 and by conductors 31 and 32 to lineL Upon closure of the contacts 26 26 and 26 of switch 26 a circuit iscompleted forv the motor 15 ,said circuit extending from lines L L and Lthrough conductors 32, 33 and 25 and conductors 32, 33 and 25 throughsaid contacts to the respective terminals of said motor 15 Also uponenergization of motor 15 the windings of electromagnetically operatedvalves 7 and 16 are energized to open said valves simultaneously withthe initiation of operation of pump 15, said windings being connected inparallel relation across a pair of the motor terminals. Assuming a givenadjustment of valves 7* and 1t the pump 15 will draw lean gas or airthrough conduit 14 and rich gas through conduit 7 at volumetricallyproportioned rates,said gases being thoroughly mixed and then dischargedthrough conduits 16 and 11 to tank 13.

.Also upon energization and closure of switch 26 the contacts 26 thereofwill act through conductors 34 and 35 to pre-set the energizing circuitsof a reversible motor 36 for completion to operate the latter in onedirection or the other for opening or closing valve 7' to vary the rateof now of rich gas through branch conduit 7 in accordance with thedeterminations of a relatively quick-acting calorimetric device 37,thelatter having permanent connections with lines L L as indicated at 38and 39. As will be noted, the valve 6 is likewise splined to theoperating shaft of valve 7 whereby like adjustments of said valves aresimultaneously effected-suitable speed-reducing gearings 36* beingpreferably interposed between motor 36 and said operating shaft.

The calorimetric device 37 will preferably be of the character describedand claimed in my copending application, Serial No. 540,863, filed May29, 1931, although it is to be understood that any other suitable formof calorimeter may be employed if desired. Said calorimeter 37 isprovided with a motor 37 which drives a pair of pumps (not shown), oneof which is adapted to withdraw through conduit 37 a continuous sampleof the mixed gases and the other of which supplies a volumetricallyproportioned stream of combustion air, said mixed gas sample and saidstream of air being supplied to a burner of suitable form; saidcalorimeter being provided with well known means including agalvanometer the needle of which is adapted to remain in an intermediateor neutral position so long as the total heating value per unit volumeof the mixed gas sample is equal to the value preselected. Upon adecrease inthe total heating value per unit volume of the mixed gassample the galvanometer needle is deflected a direction and to a degreeto cause operation of motor 36 in a direction to effect the requireddegree of opening of valve 7 (valve 6 being correspondingly adjustedsimultaneously) whereby the required degree or increase in the totalheating value per unit volume of the gas mixture is insured. Similarly,upon an increase in the total heating value per unit volume of the gasmixture the calorimeter elements function in a known manner to effectoperation of motor 36 in the reverse direction to partially close valve7* (and valve 6*) thus maintaining said total heating value of the gasmixture substantially constant.

If the rate of demand for the gas mixture is greater than the rate ofsupply thereof by pump 15, obviously the pressure within tank 13 willdrop to a still lower value and the other pressure responsive device iscalibrated to respond under such conditions to effect engagement of itscontactor 18 with stationary contact 18, thus completing an energizingcircuit for the winding of relay 40,which circuit may be traced fromline L by conductors 25 and 24 through contactor 18 and contact 18",conductor 41 through said winding, thence through a suitable protectiveresistance and conductor 20 to line L Contacts 40 of said relay arethereupon closed. to provide a maintaining circuit for the windingthereof (said maintaining circuit shunting the contactor 18 and contact18 as will be obvious). Also upon closure of contacts 40 of said relay acircuit is completed for the operating winding 43 of switch 43, saidcircuit extending from line L by conductors 25, 24 and 44 through saidcontacts 40, conductor 45 through contacts 29, 29 and 29 of transferswitch 29, conductor 46 through the winding 43, and by conductors 47 and32 to line L-".

Contacts 43 43 and 43 of said switch act upon closure thereof tocomplete the circult of motor 9, said circuit being obvious. Theoperating windings of electromagnetically operable valves 6 and 10 areconnected in parallel relation to each. other ac s a p r of the motorterminals, whereby opening of said valves is effected simultaneouslywith initiation of operation of pump 9. Contacts 43 are adapted toperform the same function as contacts 26' of switch 26, and hence theformer contacts are primarily adapted to function upon movement oftransfer switch 29 to its opposite extreme position, wherein thecontacts 29 and 29 are bridged by contact 29 to render switch 43 subjectto control by the pressure responsive switch 17.

As aforestated the valves 6 and 7* will have been adjustedcorrespondingly through the medium of the calorimetric device 37, andhence upon initiation of operation of pump 9 the mixture of rich gas andair supplied by the latter will have the desired total heating value perunit volume as preselected by the setting of the calorimetric device37,-it being understood that the valve 8 will have been previouslyadjusted to provide the same volumetric proportionality of air to richgas flowing in branch conduit 6 as is provided by the adjustment ofvalve 14 with respect to the volumetric rate of flow through branchconduit 7.

The conduit 3'7 through which the gas sample is withdrawn from conduit13 (for burning in the calorimeter 3'7) is preferably provided with apressure regulating device 37 of the character described and claimed inPackard. Patent No. 1,852,330, dated April 5, 1932,the arrangement beingpreferably such that the gas sample is supplied to the calorimeter atsubstantially atmospheric pressure, to correspond with the pressure ofthe combustion air.

When the pressure within tank 13 reaches the desired maximum value, theleft-hand pressure responsive device effects movement of its contactor18 to the right into engagement with contact 18 This short circuits thewinding of relay 40, with consequent opening of the contacts 40 fordeenergization of switch 43 and stopping of motor 9 ,the windings ofsolenoid valves 6 and 10* being simultaneously deenergized to permitclosure of said valves whereby leakage of the rich gas or of the gasmixture is prevented. If the rate of supply of mixed gases by pump 15thereafter exceeds the demand, the right-hand pressure responsive devicewill effect movement of its contactor 17 into engagement withcontact 17with consequent deenergization of relay 19, and the contacts 19 of thelatter will open to deenergize switch 26 for stopping of motor 15,solenoid operated valves 7 and 16 being simultaneously deenergized andclosed to prevent leakage as aforedescribed.

It will be understood that under normal load or demand conditions thepump 9 will remain inactive, and hence the same is rendered accessiblefor inspection or repair without interruption of the normal gas mixingoperations. In like manner the pump 15 may be rendered inactive underless than peak load conditions by moving the switch 29 to its oppositeextreme position, thus transferring the initial pumping operation to theunit comprising pump 9. Transfer switch 29 may be utilized in a likemanner to periodically transfer the major burden from one gas mixing orpumping unit to the other, whereby the wear upon the units throughout along period of time is substantially equalized.

While I prefer to employ motors 9 and 15 of substantially constantspeed, it will be apparent to those skilled in the art that by my novelarrangement of parts such provision is not necessary, since it iscontemplated that the rich gas branch conduits 6 and 7 and by insertingsimilar flow-controlling valves in the air conduits'B and 14, preferablyin advance of the points of junction of the latter with said branchconduits 6 and 7. While I have described my control system asparticularly applied to the proportioning and mixing of rich gas andair, it is to be understood that a lean gas or gases other than air maybe utilized with equal facility and accuracy in the production of a gasmixture of predetermined heating value per unit volume.

The method of and apparatus for mixing gases illustrated in Fig. 2 areessentially like the method and apparatus described with reference toFig. 1, but differ therefrom in certain details of construction and inthe mode of operation of the control elements. In Fig. 2 the tank 50designates a source of rich gas supply, as for instance a tank partiallyfilled with liquid butane, the vapor of which is forced by its ownpressure through a conduit 51 shown as having three branches 51 51 and51, which respectively lead to differential-pressure-operated valves 52,53 and 54. Said valves (which are in general of a well known form) maybe of identical size. The valve 52 is shown more in detail as comprisinga diaphragm 52 to which is attached the element 52 the position of whichcontrols the rate of flow of the rich gas through branch Sl t-as:

suming open positioning of an electromagnetically operable valve 52 andproper adjustment of a manually operable valve 52 The valve 52 includesa closed container 52 carrying a body of liquid 52 above the diaphragm52 said container communicating through conduits 52 and 55 with arelatively larger closed container 55 carrying a body 55 of said liquid.In this manner the level of the liquid in container 52 will bemaintained the same as that in container 55 ,the latter being providedwith a movable member 56 whereby said common liquid level may be varied.

Thus with electromagnetically operable valve 52 in open position branchconduit 51 is in communication with a relatively large conduit 57, thelatter serving as a mixing chamber for the rich and lean gases suppliedby each of the gas making units, and as a distributing conduit for themixed gases. The lower side of diaphragm 52 is shown as subjected to thepressure conditions on the downstream side of valve 52', as by means ofthe relatively small conduit 52, piping 58 being provided whereby theliquid in chamber 52 is subjected to the pressure conditions existing inconduit 57. By the arrangement illustrated a predetermined pressure dropacross valves 52 and 52 is insured, said pressure drop being variableautomatically in accordance with variations in the level of liquid 52.The elements of -the differential-pressure-operated valves 53 and 54function in'a like manner,it being noted that piping 58 likewisecommunicates with the consaid unit will normally be operatedcontinuously, although subject to the automatic control hereinafterdescribed. Thus I have shown three pressure-responsive switches 59, and61 all of which are subjected to the pressure conditions within conduit57, said switches being calibrated to respond sequentially underdifferent pressure conditions corresponding to variations in the rate ofdemand for the gaseous mixture. The contactor 59 of switch 59 is shownin engagement with stationary contact 59*, thus completing an energizingcircuit for the operating winding of a relay 62, which circuit may betraced from line L through knife switch 63, contactor 59 and contact 59conductor 64 through said winding, and by conductors 65 and 66 to line LContacts 62 of said relay provide a maintaining circuit thereforshunting said contactor 59 and contact 59 said maintaining circuit beingobvious.

Also upon closure of contacts 62 of said relay an energizing circuit iscompleted for the operating winding 67 of a switch 67, said circuitextending from line L by conductor 68 through said contacts 62 conductor69 through said winding 67, and by conductors 70 and 66 to line L Uponclosure of switch 67 the contacts 67*, 67 and 67 thereof effectcompletion of the circuit of a relatively small motor 71, said motorcircuit being obvious. The operating winding of the aforementioned valve52 is connected across a pair of the motor terminals, whereby said valveis opened simultaneously with the completion of the motor circuit.Switch 67 by closure of its contacts 67 completes circuit, throughconductors 71 and 72, for certain of the control elements of thecalorimetric device 73 (the latter being identical with the device 37described in connection with Fig. 1), certain of said control elementsbeing permanently connected with lines L and'L as shown.

The calorimeter withdraws a continuous sample of the mixed gases fromconduit 57, through conduit 74 having the pressure regulating device 74.Motor 71 operates at a substantially constant speed to drive therelatively small positive displacement pump 75 whereby a predeterminedvolumetric rate of flow of air or other lean gas to conduit 57 iseffected. Assuming careful manual adjustment of valve 52 the volumetricproportionality of the air supplied by pump 75 and the rich gas suppliedthrough branch conduit 51 will normally be such as to provide a flowinggaseous mixture in conduit 57 of predetermined heating value per unitvolume. However, the calorimeter 73 provides for a continuousdetermination of the total heating value per unit volume, and upon adecrease in such value with respect to a preselected value the controlelements will function to complete circuit for a motor 76 in a directionto cause downward movement of element 56 within container 55. Theresultant rise in the level of liquid 52 in container 52 willautomatically increase the degree of opening of valve 52 to effect therequired change in the pressure drop across valves 52 and 52 with aconsequent increase in the rate of flow of the rich gas, and suchadjustment will be continued pending attainment of the required totalheating value per unit volume of the gas mixture flowing in conduit 57.

It will be apparent that the aforedescribed movement of member 56 withincontainer 55 effects a like change in the level of the liquid inchambers 53 and 54 even though the other gas making units are inactive.Thus it follows that if the rate of supply of the constituent fluidsthrough pump 75 and branch conduit 51 is less than the rate of demandfor the mixture the pressure within conduit 57 will drop still further,and when said pressure reaches a predetermined low value the contactor60 of device 60 will move into engagement with contact 60 This completesa circuit for the operating winding of a relay 77, whose contacts 77provide a maintaining circuit therefor shunting contactor 60 and contact60 and whose contacts 77 complete an energizing circuit for the winding78 of switch 78. Switch 78 is provided with contacts 78, 78 and 78 whichare adapted upon closure thereof to complete the circuit of a relativelylarger motor 79 driving pump 80, the operating winding of valve 53 beingconnected across a pair of the motor terminals to provide forsimultaneous opening of said valve. In this manner an additional flow ofthe constituents of the gaseous mixture is eifected,it being understoodthat valve 53 has been previously adjusted manually to provide avolumetric proportionality of said constituents corresponding to thatafiorded by the relatively smaller gas making unit aforedescribed. Anyvariation in the total heating value per unit volume of the gaseousmixture will result in the required degree of movement of member 56 tovary the rates of flow of the rich gas through branch conduits 51 and 53through automatic variation of the level of liquid in thedifferentialpressure-operated valves of the several units.

If the demand exceeds the rate of supply by the two gas making unitsaforedescribed, the pressure within conduit 57 will drop still lower,and contactor 61 of device 61 will engage contact 61 to complete theenergizing circuit of the winding of relay 81, whose contacts 81 willprovide a maintaining circuit therefor, and whose contacts 81 willcomplete a circuit for the operating winding 82 of a switch 82. Contacts82 82 and 82 will complete circuit for a motor 83 which drives a pump 84corresponding in size with pump 80. Contacts 78 of switch 78 and/orcontacts 82 of switch 82 function to complete circuit for theaforementioned control elements of calorimeter 73, in the event that thepressure responsive switch 59 is disabled through manual opening ofknife switch 63. The consequent inactivity of the relative small gasmaking unit comprising pump 75 may be utilized to provide for inspectionor repair of the latter and to prevent the normally continuous operationthereof.

A transfer switch 85 of the character described in Fig. 1 may beprovided for reversing at will the sequence in which the motors 79 and83 are rendered active, by merely subjecting the same alternately tocontrol of the respective pressure responsive devices 60 and 61. By thismeans pumps 80 or 84 may be rendered inactive selectively under low loadconditions to provide for inspection or repair thereof and to equalizethe wear thereupon, as set forth in connection with the device ofFig. 1. Upon a decrease in the demand for the gaseous mixture afterpeakload conditions, with the parts arranged as illustrated, contactor61 of device 61 will first en-- gage its cooperating contact 61 to shortcircuit the winding of relay 81 with consequent opening of the latterand opening of switch 82 for stopping of motor 83, valve 54 beingsimultaneously closed to prevent leakage of the rich gas from branchconduit 51. A further increase in pressure of the fluid mixture inconduit 57 will cause engagement of contactor 60 of device 60 with itscooperating contact 60 to short circuit the winding of relay 77, withconsequent deenergization and opening of switch 78 and stopping of motor'79,-valve 53 being simultaneously closed through deenergization of itsoperating winding as will be obvious.

While as aforestated it is contemplated that motor 71 will normally beoperated continuously, nevertheless the device 59 is designed tofunction, under predetermined relatively high pressure conditions withinconduit 57, to effect engagement of contactor 59 with its cooperatingcontact 59 to short circuit the operating winding of relay 62,-whereasupondeenergization and opening of the latter the switch 67 is likewisedeenergized and opened to temporarily discontinue the operation of motor71,valve 52 being simultaneously deenergized and closed to insurediscontinuance of the supply of all of the fluid constituents to conduit57 pending the required reduction in fluid pressure in the latter.

As will be apparent the arrangement in each form of gas mixing controlsystem herein described is such that the respective units may beinitially adjusted to provide the required volumetric proportionality ofthe gaseous fluid constituents to provide a mixture of predeterminedtotal heating value per unit volume, whereas automatic and rapidadjustment of the volumetric proportionality of such constituents iseffected by the quick-acting calorimeter aforedescribed. Moreover, itwill be noted that the adjustment of all gas making units is effectedsimultaneously regardless of whether one or more of the units is activeat the time such adjustment is effected, so that any units subsequentlyrendered active to meet an increased demand for the gaseous mixture willbe initially prepared to supply the fluid constituents in the propervolumetric proportionality to afford a mixture of the desired totalheating value per unit volume. This is an imprtant feature since itinsures against any substantial variation in the total heating value perunit volume of the mixture flowing into the distribution line or intothe mixed gas storage tank or container.

The motor 76 in Fig. 2 is of course preferably provided with speedreducing gearing designated by the reference character 76*, and suitablegearing '76 is provided for connection thereof with shaft 76. Container55 is preferably rendered fluid tight as by means of a removable cover55 which provides a suitable fluidtight bearing for said shaft- '76,thelower end of said shaft having a bearing at 55 within said container.Member 56 which is preferably hollow to minimize the weight or inertiathereof is provided with an internally threaded portion 56 whichcooperates with the threaded portion '76 of shaft 76 Member 56 ispreferably closed or sealed at its upper end, as indicated at 56, toinsure against ingress of liquid thereinto. A coiled spring 56*surrounds bearing 55 to cushion the movement of member 56 to its lowerextreme position. As will be apparent the arrangement is such that thedriving engagment between the threaded portion "id of shaft 76 andmember 56 is automatically interrupted upon operation of shaft 76 beyondthe desired limits, thus insuring against possible injury to the partsaforedescribed.

What I claim as new and desire to secure by Letters Patent is: v

1. In a method of mixing combustible gases of unlike quality or totalheating value per unit volume, the steps which comprise effecting oneflow of one of the constituents of a combustible mixture of fluids tosatisfy a given rate of demand for the latter and automaticallyeffecting one or more additional flows of said one of said constituentsupon given increase or increases in the rate of demand for said mixture,effecting a corresponding number of flows of another of the constituentsof said mixture in each instance, initially volumetrically proportioningthe flows of said constituents to provide a mixture of predeterminedtotal heating value per unit volume, and automatically varying thevolumetric proportionality of the flows of the respective constituentsin accordance with and to compensate for variations in. the totalheating value per unit volume of said combustible mixture with respectto a preselected value.

2. In a method of mixing a plurality of combustible fluids of unlikequality or total heating value per unit volume to provide a combustiblefluid mixture of substantially constant total heating value per unitvolume whose volumetric rate of flow varies in accordance with thedemand therefor, the steps which consist in providing a number of unitseach of which is adapted when 01)- erated to effect flows of all of theconstituent fluids in predetermined volumetric proportionality to eachother, subjecting said units to influence of pressure conditions whichvary in accordance with variations in demand for the mixture, wherebysaid units are rendered individually or jointly operative to maintainsaid pressure conditions substantially constant, continuouslyascertaining the instantaneous total heating value per unit volume ofthe mixture supplied by the active units, and automatically andsimultaneously adjusting said units in accordance with variations insaid value with respect to a predetermined value, whereby the volumetricproportionality of the constituents of the mixture supplied by each unitis modified to maintain said value substantially constant.

3. The method which consists in automatically initiating operation ofone or more of a plurality of gas mixing units in accordance withvariations in pressure conditions incident to variations in demand forthe mixture, each unit when operated being normally adapted to effect aplurality of flows of gaseous fluids of unlike quality or total heatingvalue per unit volume, said flows being definitely proportionedvolumetrically to provide a, gaseous mixture of predetermined totalheating value per unit volume, withdrawing a continuous sample of thegaseous mixture supplied by the active units and calorimetricallyascertaining the total heating value per unit volume thereof, andautomatically varying the relative rates of flow of the constituentfluids supplied by the respective unitsin accordance with and tocompensate for the ascertained variations in said total heating valuewith respect to a given value.

4. The method which consists in automatically initiating operation ofone or more of a plurality of gas making units in accordance withvariations in pressure conditions incident to variations in demand, eachunit when operated being normally adapted to efiect a flow of relativelyrich gas and a flow of relatively lean gas in definitely proportionedrelation by volume, withdrawing a continuous sample of the mixture ofgases and calorimetrically ascertaining the total heating value per unitvolume thereof, and automatically varying the rates of the individualflows of rich gas per unit volume with respect to a preselected value.

5. In a method of maintaining substantially constant the total heatingvalue per unit volume of a composite flow of combustible gaseous fluidsto be supplied from one or more gas making units, each unit beingnormally adapted to effect a flow of relatively rich gas and a flow ofrelatively lean gas in definite volumetric proportionality to each otherto provide a gaseous mixture of predetermined total heating value perunit volume, said units being operable automatically either individuallyor jointly in response to variations in demand for the gaseous mixture,the steps which consist in continuously ascertaining calorimetricallythe total heating value per unit volume of the gaseous mixture, andsimultaneously adjusting the rates of the individual flows of relativelyrich gas in accordance with and to compensate for variations in saidtotal heating value per unit volume of the gaseous mixture with respectto a preselected value.

6. In a mixing control system for combustible gases, in combination, aconduit for mixed gases, a plurality of units each adapted when operatedto supply to said conduit a plurality of constituent gaseous fluids ofunlike quality or total heating value per unit volume, each of saidunits being initially adjusted to insure a predetermined volumetricproportionality of the constituent fluids supplied thereby whereby agaseous mixture of predetermined total heating value per unit volume isprovided, means for rendering said units operative either individuallyor jointly in response to variations in pressure of themixture in saidconduit as an incident to variations in demand for the mixture, meansincluding a calorimeter for continuously withdrawing and burning asample of the mixture whereby the instantaneous total heating value perunit volume of the mixture is ascertained, and means controlled by saidcalorimeter for adjusting each of said units whereby the volumetricproportionality of the fluid constituents supplied by the latter isvaried in accordance with and to compensate for variations in the totalheating value per unit volume of said gaseous mixture.

7. In a gas mixing control system, in combination, a plurality of unitseach comprising a positive displacement pump adapted when operated toeffect a flow of air or other lean gas and each unit also comprising abranch conduit through which rich gas is adapted to flow inpredetermined volumetric proportionality to said flow of air or otherlean gas, pressure responsive means operable automatically forcontrolling the operation of said units either individually or jointlyin accordance with and to compensate for variations in the demand forthe gaseous mixture, and means responsive to variations in the totalheating value per unit volume of said gaseous mixture with respect to agiven value for automatically varying the volumetric proportionality ofthe flows of rich gas and air or other lean gas supplied by each and allof said units, whereby the total heating value per unit volume of saidgaseous mixture is maintained substantially constant.

8. In combination, a plurality of gas making units, each unit whenoperated being adapted to individually effect volumetricallyproportioned flows of fluids of unlike quality to normally provide afluid mixture of predetermined total heating value per unit volume, acommon discharge conduit for said units, means for selectively renderinssaid units operable either individually or matically varying thevolumetric proportionality of said fluids of unlike quality inresponse'to variations in the total heating value per unit volume ofsaid fluid mixture, whereby said total heating value per unit volume ismaintained substantially constant.

9. In combination, a distributing conduit for a composite combustiblefluid, pressure responsive means associated with said conduit, aplurality of gas mixing units, means controlled by said pressure meansfor rendering said units either individually or jointly operable inresponse to the combustible fluid demand, each unit when operated beingadapted to effect a substantially constant volumetric rate of flow of acomposite combustible fluid, the constituent flows of said compositecombustible fluid being volumetrically proportioned relatively to eachother to normally provide a mixture of predetermined total heating valueper unit volume, calorimetric means for continuously ascertaining thetotal heating value per unit volume of said mixture, and meanscontrolled by said calorimetric means for varying the volumetricproportionality of said constituent flows whereby said total heatingvalue per unit volume is maintained substantially constant.

10. In combination, a distributing conduit for a composite combustiblefluid, pressure responsive means associated with said conduit, aplurality of gas mixing units, means controlled by said pressure meansfor rendering said units either individually or jointly operable inresponse to the combustible fluid demand, each unit when operated beingadapted to effect a substantially constant volumetric rate of flow of acomposite combustible fluid, the constituent flows of said compositecombustible fluid being volumetrically proportioned relatively to eachother to normally provide a mixture of predetermined total heating valueper unit volume, calorimetric means for continuously ascertaining thetotal heating value per unit volume of said mixture, means controlled bysaid calorimetric means for varying the volumetric proportionality ofsaid constituent flows whereby said total heating value per unit volumeis maintained substantially constant, said last mentioned meanscomprising a plurality of flow regulating valves associated with therespective units, and power means for simultaneously effecting likeadjustments of all of said regulating valves.

11. In combination, a distributing conduit for a composite combustiblefluid, pressure responsive means associated with said conduit, aplurality of gas mixing units, means controlled by said pressure meansfor rendering said units either individually or jointly operable inresponse to the combustble fluid demand, each unit when operated beingadapted to efiect a substantially constant volumetric rate of flow of acomposite combustible fluid, the constituent flows of said compositecombustible fluid being volumetrically proportioned relatvely to eachother to normally provide a mixture of predetermined total heating valueper unit volume, calorimetric means for continuously ascertaining thetotal heating value per unit volume of said mxture, means controlled bysaid calorimetric means for varying the volumetric proportionality ofsaid constituent flows whereby said total heating value per unit volumeis maintained substantially constant, said last mentioned meanscomprising a plurality of flow regulating valves associated with therespective units, and power means for simultaneously effecting likeadjustments of all of said regulating valves, each of said valvesincluding means for automatically maintaining a predetermined pressuredrop across a restriction located in a fluid supply line of eachrespective unit.

12. In combination, a distributing conduit for a composite combustiblefluid, pressure responsive means associated with said conduit, aplurality of gas mixing units, means controlled by sa'd pressure meansfor rendering said units either individually or jointly operable inresponse to the combustible fluid demand, each unit when operated beingadapted to efiect a substantially constant volumetric rate of flow of acomposite combustible flud, the constituent flows of said compositecombustible fluid being volumetrically proportioned relatively to eachother to normally provide a mixture of predetermined total heating valueper unit volume, calorimetric means for continuously ascertaining thetotal heating value per unit volume of said mixture, means controlled bysaid calorimetric means for varying the volumetric proportionality ofsaid constituent flows whereby said total heating value per unit volumeis maintained substantially constant, said last mentionedmeans'comprising a plurality of flow regulating valves associated withthe respective units, and power means for simultaneously effecting likeadjustments of all of said regulating valves, each of said valvesincluding means for automatically maintaining a predetermined pressuredrop across a restriction located in a fluid supply line of eachrespective unit, the means for adjusting said valves including adisplaceable body of liquid common thereto.

13. In a gas mixing control system, in combination, a plurality of gasmaking units, a common discharge condut for said units, each unit whenin operation being adapted to supply a gaseous fluid at a substantiallyconstant volumetric rate, means responsive to operation of each unit foreffecting a separate flow of rich gas in definite volumetricproportionality to said first mentioned fluid for mixture with thelatter, calorimetric means for continuously ascertaining the totalheating value per unit volume of the mixture in said conduit, and meanscontrolled by said calorimetric means for simultaneously adjustingand/or pre-adjusting the volumetric rates of supply of said rich gas bythe respective units, whereby the total heating value per unit volume ofthe mixture within said conduit is maintained substantially constantunder conditions of individual and/or joint operation of said gas makingunits.

14. In combination, a plurality of gas mixing control devices, eachdevice comprising means for eifecting a plurality of volumetricallyproport oned flows of fluids of unlike quality or total heating valueper unit volume to normally provide a fluid mixture of predeterminedtotal heating value per unit volume, means responsive to pressurevariations of the fluid mixture, as an incdent to variations in demandfor the latter, to effect operation of said control devices eitherindividually or jointly, means for ascertaining the total heating valueper unit volume of the fluid m xture, and common means controlled bysaid last mentioned means for varying the volumetric proportionality ofthe flows effected by each of said control devices, whereby the totalheating value per unit volume of said fluid mixture is maintainedsubstantially constant.

15. In a gas making and distributing system, in combination, a pluralityof gas making units, a common source of rich gas supply therefor, meansindividual to each unit and operable in response to operation thereofrespectively to effect a predetermined volumetric rate of flow of therich gas, each unit also including means for effecting a flow of leangas or air in definite volumetric proportionality to the flow of richgas for mixture with the latter, pressure means operable in response tovariations in demand for the mixture to selectively effect operation ofsaid units either individually or jointly whereby the pressure of themixture is maintained substantially constant under conditions ofvariation in demand for the latter, means for continuously ascertainingthe total heating value per unit volume of said mixture, and meanscontrolled by said last mentioned means for varying the volumetric rateof flow of the rich gas in accordance with and to compensate forvariations in said total heating value per unit volume with respect to agiven value. 00

16. In a butane gas mixing control system, in combination a source ofbutane gas supply, a plurality of branch conduits communicating withsaid source, means operable automatically to maintain substantiallyconstant pressures of gas in the respective branch conduits, a pluralityof positive displacement pumps having air intake conduits with which therespective branch conduits communicate, manually operable means forinitially adjusting the relative rates of flow of gas and air to therespective pumps to normally provide a gaseous mixture of predeterminedheating value per unit volume, a common discharge conduit for saidpumps, means responsive to pressure conditions within said dischargeconduit for rendering said pumps operable either individually or jointlyto thereby maintain the pressure within said conduit substantially.constant under conditions of variation in demand for the gaseousmixture, means for continuously ascertaining the instantaneous totalheating value per unit volume of the gaseous mixture within saidconduit, and means controlled by said last mentioned means forsimultaneously varying the relative rates of supply of gas and air toeach of said pumps, to thereby maintain the total heating value per unitvolume of the gaseous mixture substantially constant under allconditions.

17. In a butane gas mixing control system, in combination, a source ofbutane gas supply, a plurality of'branch conduits communicating withsaid source, a valve in each of said branch conduits, pressure operateddevices associated with the respective valves to maintain substantiallyconstant pressure drops across restrictions respectively associated withthe latter, manually operable means associated with the respectivebranch conduits for initially adjusting the volumetric rates of flowtherethrough, a discharge conduit with which each of said branchconduits is adapted to communicate, means including normally closedelectromagnetically operable valves individual to each branch conduitfor normally interrupting communication between the same and saiddischarge conduit, a plurality of power driven positive displacementpumps, the discharge ends of which likewise communicate with saiddischarge conduit for supplying air or other lean gas thereto, meansadapted upon' operation 150 mixture, and means controlled by said lastmentioned means for simultaneously varying the pressure drops acrosssaid restrictions aforementioned, whereby the volumetric rates of flowof butane gas in said branch conduits are adjusted to maintain the totalheating value per unit volume of the gaseous mixture substantiallyconstant.

EDWIN X. SCHMIDT.

